Die head



April 11, 1939. s. w. MA THlAS ET AL DIE HEAD Filed June 15, 1936 6 Sheets-Sheet 1 mam W3 Wda W5 W1 MA a m Z ATTORNEYS A ril 11, 193.9.

s. w. MALI'HIAS ET AL 1113 HEAD 6 Sheets-Sheet 2 Filed June 15, 1936 ATTORNEYS April l, 1939.

s. w. MATHIAS DIE HEAR) Filed June. 15,

ET AL 2,154,006

1936 6 Sheets-Sheet 3 iNvENToR, J'Qwuw/ W/ i 2/2/34 ATTORNEYS April 1939- w. MATHIAS ET AL DIE HEAD Filed June 15, 1936 6 Sheets-Sheet 4 a c w L a M II- M. M m I U U M M M W I m y M l ATTORNEYS April 11, 1939. s. w. MATHIAS Er- AL DIE HEAD 6 Sheets-Sheet 5 Filed June 15, 1936 a a w a w M 1 \\\\\\\&

Patented Apr. 11, 1939 DIE HEAD Samuel W. Mathias and mlbum A. Hollengree'n,

Waynesboro, Pa., assignors to Landis Machine Company, Waynesboro, Pai, a corporation of Pennsylvania Application June 15, 1936,8erial No. 85,419

28 Claims.

The present invention relates to threading die heads, and it is more particularly concerned with die heads for cutting threads onbolts, screws, pipe and other articles of work, the die head carrying slidable chasers and being automati cally operable to release the chasers from the work when the chasers, in threading up on the completed thread, tend to pull the head forwardly with respect to its support.

Although die heads of this general character have been heretofore proposed, they have not been altogether successful because pull-ofi action has required considerable forces to be applied to the chasers which not only make the head difii- 'cu1t to open, but the chasers have also been found to mark the flanks of the thread cut on the work. Some of the heads of the prior art are also open to the objection that when they are adjusted to handle work of different diameters the head-opening springs are placed under different degrees of compression, with the result that the head manifests varying operating characterlstics.

. Other heads of the prior art are open to the still further disadvantage of requiring an exceedingly long pull-off action, and are diflicult to restore to closed condition.

It is accordingly the primary object of our invention to overcome all of the disadvantages of the prior art and to provide a novel self opening die head of rugged design which will rigidly hold the chasers in cutting position, which will automatically release the chasers with a minimum pull-ofi travel, and with a pull-oi! force of low magnitude.

Another major object is to provide a die head having opening springs and pull-back springs, and means for pushing the closing ring toward locking position against the action of the open- 40 ing springs and simultaneously supplementing the head retracting action of the pull-back springs, whereby the latter may be comparatively smaller than the opening springs. Another important object is to provide, in a die head having movable chasers and an axially movable springeurged member for controlling the position of the chasers, the member being lockable ina fixed axial position, a novel mechanism for adjusting the head for different diametrical sizes a of work without varying the degree of stress in the springs; whereby the head manifests constant operating characteristics irrespective of the head size adjustment. v A further object is to provide a novel die head whereby right-hand and left-hand threads may be generated using the same head.

Another object is to provide a novel locking mechanism for use with die heads of the type embodying an axially slidable head. 5

A still further object is to provide a novelopen ating ring assembly for closing automatic die heads of the character embodying an axially slidable head.

Our invention further aims to provide a. novel 10 chaser holder and closing ring assembly for die heads embodying a head having radially extending holder guideways, the parts being so designed that the holders may be inserted in the guideways and connected to the closing ring in succession. 15

Another object is to provide a die head whose parts are effectively sealed against extraneous material, whereby the head has a long life.

i A further object is to provide, in a die head mounted for axial movement and having a closing 20 ring. urged toward head-opening position by a spring, means for pushing the closing ring forwardly toward head-closing position against theaction of the spring and for also moving the head rearwardly. 25

Further objects of our invention will become apparent as the specification proceeds in connection with the annexed drawings, and from the appended claims.

In the drawings, Figure l is a side elevational 30 view of the die head of our invention with the head in locked condition and illustrates one of the operating rollers with its controlling arm in section and disposed in retracted condition.

Figure 2 is a front elevational view of the die 35 head of Figure 1. s

Figure 3 is a front view of the die head shown in Figure 2, but shows the head as it appears when the chaser holders are removed and also illustrates the operating rollers, the head being 40 in locked condition. a

Figure 4 is a sectional viewon the line 4-4 of Figure 3, and also illustrates the parts of the head in locked condition ready to perform the threading operation. 4

Figure 5 is a sectional view taken on line 5-5 of Figure 8 and illustrates the parts as they appear just after they have been brought into locked condition and before the operating rollers have been retracted.

a Figure 6 is a rear elevational viewof the die head of our invention.

Figure 7 is a sectional-view similar to Figure 5 taken substantially on the line 55 of Figure 8 55 t plurality of chasers and which is mounted for but illustrates the parts as they appear when the die is in open condition.

Figure 8 is a transverse sectional view taken substantially on the line 8-8 of Figure '7 and illustrates the parts in unlocked condition with the die head open.

Figure 9 is a fragmental elevational view of the joint between the main head body and the auxiliary head body of our die head and certain parts have been removed in order to facilitate the disclosure.

Figure 10 is a fragmental longitudinal view of the die head shown in Figure 4 and illustrates the manner in which the chaser holders cooperate with the operating prongs of the closing ring, the chaser holders shown in the position they assume when the head is open in non-cutting condition.

I Figure 11 is a fragmental sectional view taken on line il--l| of, Figure 10, and illustrates how the chaser holders cooperate with the prongs of the closing ring.

Figure 12 is a view similar to Figure 10, but illustrates how the chaser holders are applied in the head and illustrates the prongs of the closing ring in. the position they assume just before they engage the chaser holders.

Figure 13 is a bottom plan view of one of the chaser holders used in our head.

Figure 14 is a face view of the chaser holders.

Figure 15 is a sectional view through one of the chaser and chaser holder assemblies and is taken substantially on the line l5|5 of Figure 2.

Figure 16 is an enlarged partial fragmental sectional view corresponding to Figure 5 and shows the parts in locked condition, certain of the parts being omitted and other parts being illustrated in phantom lines in order to clarify the disclosure.

Figure 17 is a view similar to Figure 16 but illustrates the latch members in retracted or unlocked condition, and the other parts are shown as they appear at the instant of release, 1. e., the position they assume when the head has just been unlocked and the ring and chaser holders are about to move to their retracted position under the influence of the opening springs.

Figure 18 is a view similar to Figures 16 and 17, but shows the parts in the position they assume after complete opening movement of the rings and chaser holders has taken place.

Figure 19 is a fragmental sectional view showing the head and support in disassembled condition, but illustrating the locking ring in locked position on the head.

With continued reference to the drawings, wherein like reference characters have been employed to designate like. parts throughout the several views thereof, in generalour die head comprises a main head body H which carries a limited axial movement on an auxiliary head body'or support S. A closing ring C slidably mounted on the head is operative to move the chasers inwardly into cutting position when it is slid forwardly on the head and is operative to move the chasers outwardly to non-cutting" position when it is slid rearwardly on the head. Springs normally urge the closing ring rearwardly and it is adapted to be locked in chaserclosing position by means of a locking ring L which is slidably mounted upon the head and the support. The closing ring carries a plurality of slidable latches which are adapted to be automatically forced into unlatched position when the head moves forwardly a predetermined distance on the support.

The various parts of the device will now be described, and for convenience the description will be divided up into various headings.

Head and chaser assembly Although the threading die of the invention may be used in a horizontal position as well as a vertical position we have for convenience illustrated the head as being mounted with its axis vertical, but in view of the fact that movement of the head upward in the various figures corresponds to a forward movement when the die is horizontal, and moves the chasers toward It. Work, this direction of movement will be hereinafter referred to as forward movement and reverse direction will be referred to as rearwad movement.

Head H is mounted for axial movement and to this end is provided a cylindrical bore II which fits over a cylindrical projection l2 provided on support S. Support S constitutes an auxiliary head body but for brevity it will be hereinafter referred to as a support and it may be held for example on the spindle of an automatic forming and threading machine by means of screw threads I3.

The front face of head H is provided with four angular slots I5 in which the chaser holders are slidably mounted. With reference to Figures 10 to 15, inclusive, the chasers I6 and their holding blocks I! are shown in Patent No. 1,951,290, granted March 13, 1934, and as they per se form no part of the present invention they will not be described in detail herein. Sufiice it to say that each chaser I6 is releasably clamped in an angular groove l8 in holder IT by means of a clamp l9 which is forced down against the chaser holder l1 and the chaser by means of cap screw 2| which is threaded into the holder. The base of each holder I7 is provided with an enlarged portion 23 having faces 24 and 25 which closely cooperate with the sides of slots ii. The chaser holders are accordingly mounted for inward and outward sliding movement on head H and chasers iii are adjustably and detachably secured to the chaser holders. The chasers may be adjusted toward and away from the work by set screws 26 which are threaded into the holders.

Chaser operating or closing ring grooves l5. The closing ring is provided with a plurality of forwardly extending prongs 29 which slidably project through openings 28 and therebyv restrain the closingring against angular movement with respect to the head. The closing ring prongs cooperate with the chaser holders in the manner shown in Figures 10, 11 and 12. With reference to these figures, each prong is provided. with an inclined surface '33 which cooperateswith the bottom wall 34 of a recess 35 formed in each chaser holder. Each groove 35 0f holder 11 is provided with an inwardly extending rib 38 which slidably cooperates with a groove 35 provided in each prong 29. I. v

It is apparent that by moving closing ring C forwardly, face 33 of prong 29 will engage the bottom of recesses 35 in holders l1 and move them inwardly. When ring C is moved rearwa d] a surface 4| provided on each prong will engage rib 36 and move the holders outwardly. .In order to facilitate assembly of the holders with the prongs, we have beveled away the mouths of grooves 39 of the prong at 42 in order to guide ribs 38 into place.

In the past, in die heads of this type, the prongs of the closing ring were always of the same length and consequently when changing holders or chaser parts, it was necessary in assembling the holders on the head, that the prongs would all enter the blocks at the same time. This was a very tedious operation and required time, especiallywhen the blocks were somewhat oily, because un der such conditions there is nothing to hold one holder in place when locating the remaining holders. 'In our die head this disadvantage has been overcome by starting with one prong and making each successive prongslightly shorter and by beveling the mouths of grooves 36.

With this construction it is possible to put one holder on the head at a time. The first holder is inserted with its rib 38 in slot 66 over the longest prong, which is appropriately marked to distinguish it from the others. The holder is then pushed inwardly on the base of the head until the prong enters the holder. When one holder has been put in place on the head as described, the next holder is inserted in the same manner. This effects a material saving in the time necessary to change the holders and therefore reduces the length of time the head is out of production.

Although chasers l6 and holders H are separate members, when they are assembled and clamped in place they constitute a single member and the term chaser, as employed in the appended claims, is intended to embrace the chasers plus their holders.

Adjusting ring' assembly Threaded on the outer periphery of closing ring C is an adjusting ring 45 which is adapted to be locked in any desired adjusted position thereon by means of a set screw 46 and a soft metallic plug 41 which is made of brass or copper, in order to prevent it from damaging the threads of the closing ring. v v

The adjusting ring is provided with a forwardly extending flange 46 which is telescoped within a rearwardly. extending flange 49 provided on ,head H. These flanges are disposed'in sliding engagement, but preferably fit sumciently closely to prevent foreign matter from working'its way into the head. Adjustingring 45 is also provided with a radial flange 5| and a rearwardly directed flange 52. The forward face of flange 5| takes the load of the die opening springs and its rear face takes the forces exerted by the locking mechanism. Flange 52 form's a housing for the looking mechanism and other parts of the device so as to completely seal the head against foreign matter as will presently appear.

Closing ring C is urged rearwardly, so as to --normally tend to bring the chasers into inopera- 'tive or non-cutting position. To this end preferably two compression springs 54 react at one end against the bottom of recesses 55 provided in the head and contain plungers 56 whose heads act directly against flange 5| of the adjusting ring. As seen in Figures 5 and 7, springs 64 extend freely through openings 51 in closing ring C, v

with the result that they exert no force upon the closing ring directly.

Assuming that adjusting'ring 45 is locked in a predetermined axial position by the latching mechanism to be hereinafter described, and it is desired to vary the diametrical size of the die to handle smaller or larger work, set screw 46 is loosened and ring 45 is rotated in theproper direction to move closing member forwardly or rearwardly to bring about the desired diametrical size. In order to facilitate making the adjustment, graduations 56 are preferably provided on head H which may be lined up with a reference mark 59 on the adjusting ring. Assuming that a smaller diametrical size has been obtained, by moving ring C forwardly, set screw 46 is again locked in place.

It should be' observed that during this operation the predetermined compression of springs 54 has not been varied because the adjustment has merely resulted in closing ring C moving forwardjusting ring against which spring 54 acts has not been changed. This highly desirableresult is brought about by allowing springs 54 to=project freely through apertures in the closing ring, and

it should be observed that pins 56, which flt rather tightly within the spring, prevent the springs from being deflected out of line when the adjusting ring is rotated, and they also provide hardened smfaces which smoothly ride upon flange 5!. In order to facilitate turning the adjusting ring, it is preferably provided with a plurality of sockets 6| with which a spanner wrench may be engaged.

Although the closing ring and the adjusting ring constitute two separate parts, they are rigidly connected and function as a single member duringnormal operation of the head, and they accordingly will be collectively referred to hereinafter, and also in certain of the appended claims, as a control ring.

Locking ring Slidably mounted in recesses 65 are block-like latch members 61 having radial bores 68 provided therein. Disposed in bores 66 are compression springs 69 which bear against the bottom of the bore and urge the heads of plungers II contained therein outwardly into engagement with flange 52 of the arflusting ring. Plungers II are utilizedto maintain springs 66 in proper assembled relationship with the latches when the adjusting ring is rotated to adjust the die. As seen in Figure 4, the locking ring is restrained against rocking about the axis of the head by means of a key I2 fitted in a slot in support S and slidably cooperating with a groove 13 in the locking ring.

Although we prefer to employ slidable latches it Auxiliary head body or support As seen in Figures 5, 7 and 9, support S is provided with a cylindrical portion 15 and a larger diameter cylindrical portion 18. Opening into both portions 15 and 18 are a plurality of axially extending open-sided recesses 11. Located forwardly of portion 15 of support 8 is a radial face 18 against which ,a plurality of abutments 18 provided on head H are adapted to abut when the head is in retracted position. Head H is provided with a plurality, preferably four, rearwardly extending prongs or fingers or finger-like projections 88 which are slidably disposed between the side walls of recesses 11. In view of the fact that prongs 80 engage comparatively large areas o recesses 11 they adequately resist the turning efforts set up by the threading operation and accordingly positively restrain the head against rocking movement with respect to support S. The locking latches cooperate with abutment faces provided on the rearwardly projecting prongs of the head and are adapted to be automatically unlocked by releasing faces provided on support S when the head is moved forwardly with respect to the support. This structure will now be described.

Referring particularly to Figures 9 and 19, each prong 88 is provided with a recess 82 having a forwardly facing abutment wall 83, which cooperates with the inner end of its corresponding latch 81 in the manner shown in Figure 19. Each prong 88 is also provided with a flat riding face 84 upon which its latch is adapted to ride after the latches have been moved into released position. As seen in Figures 5, 16 and 19, latches 81 are engaged with walls 83 and positively restrain the locking ring, and in turn the adjusting ring and the closing ring, against rearward movement with respect to head H, and therefore the chasers are positively locked in their innermost position. This is known as the locked condition of the head.

Cylindrical surface 15 of support S is cut away either side of slots 11 and provides a recess 88 having an inclined cam face 81, which merges into a flat surface 88. Cylindrical surface 15 is also cut away to provide flat surfaces 89 each side of slot 11 to provide clearance for the latch when it has. been moved into unlocked position. These various formations are clearly seen in Figures 9 and 19. A

InFigure 9 the head is shown in retracted position with its bosses 18 engaging face 18 of support S and one of the latches 81 is diagrammatically illustrated ascooperating with abutment face "of prong 80. latch 81 is wider than prong 88, with ,the result .that it cooperates at either end with inclined faces 81.

As clearly seen in'Figure 19, the forward edge of each latch 81 is preferably provided with an inclined face it having an inclination approximately equal to the inclination of faces 81 for reducing the friction and insuring smooth operation of the latches.

I which maintains closing ring C in its forward condition, as illustrated in Figures 1, 3, 4, 9 and 16, the ychasers are locked in their innermost position and the head is ready for the threading operation.

'\1:-=,1.1ning that the'support or auxiliary head 8 rted on a turretwhicn advances the head toward the work, the head is advanced toward the work, (or the work may be advanced toward the head) at the rate determined by the lead of the particular thread being cut and the work is threaded in well known manner. When a thread of the proper length has been cut on the work, the forward motion of support S (or the work) is stopped and because the chasers are engaged with the thread being cut on the work and because the head (or work) is revolving, the chasers accordingly tend to pull themselves still further onto the work, with the result that head H moves forwardly with respect to support 8.

As the head starts forward a clearance develops between faces 19 of the head and radial face 18 of support S. It is observed that when the head moves forwardly all of the parts carried by the head are maintained in a fixed axial position by reason of the fact that latches 81 are engaged with the abutment faces on prongs 80. The chasers accordingly remain engaged with the work. As the forward movement of the head progresses, and which will be hereinafter referred to as the pull-01f action, inclined faces SI of latches 81 ride upwardly on cam faces 81 of support S, with the result that latches 81 move outwardly on abutment faces 83.

When the pull-oil. action just described has progressed to a predetermined degree, latches 81 attain the position illustrated in Figure 17, where they are carried clear of abutment faces 83. As soon as this point has been reached, the locking ring, the adjusting ring and the closing ring are quickly snapped rearwardly by the action of compression springs 54, and prongs 29 accordingly quickly move the holders and chasers into their outer position and thus disengage them from the work.

After the head has become unlocked in the manner just described, it is urged rearwardly by a pair of pull-back spring assemblies that will now be described. With reference to Figures 4 and 8, a pair of longitudinally extending bores 93, having restricted bottoms, are provided in support S and located therein are a pair of shouldered bolt members 84, which are threaded into head H with their shoulders engaging the rear face of the head. Encircling bolt members 94 are compression springs 85 which bear against the heads of the bolt members and react against the bottoms of bores 93. Springs 95 accordingly urge head H rearwardly on support S and tend to constantly keep faces 19 of the head in engagement with the radial face 18 of sup-'- port- S.

The pull-back springs are only used when the head is used in an inverted position, as on an automatic forming and threading machine, and in this case they are only employed to carry the weight of the bead, body and closing ring, so that when the threading spindle starts forward with a jerk the die head will not trip itself open. The pull-back springs play no part in the actual closing of the head and merely function as a. safety device when the head is operated in the inverted position just described.

Movement of headH away from support S is limited by the heads 91 of a pair of bolt members 88 which are threaded into head H (Figures and 7). Bolt members 88 freely extend through a pair of apertures 89 provided in the support and as seen in Figuresb and 7, these apertures open into large counterbores l8! which receive the heads of bolt members 98. It is apparent actual retraction of the head by the operating mechanism that will be hereinafter set forth.

After the head has been unlocked and the chasers released from the work in the manner just described, the parts assume the position illustrated in Figure 7 and the head is maintained in a forward position with respect to the support against the action of pull-back springs by two forces.

One force is exerted by opening springs 54, which react against the head and force closing ring C, adjusting ring 45 and locking ring L rearwardly and bring the latter into engagement with a stop face I03 provided on support S (Fig ure 4). Springs 54 accordingly in effect react against support S through locking ring L and accordingly act against the head to force it away from the support as they are stronger than holdback springs 95 which oppose this action.

The second force'is set up by the centrifugal action of the chaser holder assemblies. As the head revolves, the holders tend to slide outward in their grooves I5, but are restrainedby the prongs of closing ring C. The holders push against tapered surfaces 33 of the prongs and this force can be resolved into two components, one in a radial direction and one in an axial direction. The axial component of this centrifugal force tends to push closing ring C, adjusting ring 46 and locking ring L rearwardly, but as the locking ring abuts wall I03 of support 8, it is apparent that this force reacts against the inclined walls of grooves I5 to pull head H forwardlyand of course maintain it in its advanced position.

When forces are applied to the locking ring in order to move it forwardly into locked position, this force also tends to maintain head H in forward position, and although it would be possible to employ hold-back springs 05 of sufll cient strength to maintain head H in its rethis is highly imdesirable. as

tracted position, heavy hold-back springs make a head diilcult to open and they also cause the chasers to mark the flanks of the thread cut on the work.

when the head is used in a horizontal position no pull-back springs are needed because in this case the weight of the head body does not have a tendencyv to pullforward and unlatch the head. We employ a mechanism for independentlylbringing the parts of the head into latched condition and it will he presently described. Theld'e'al head would be one that opened easily withthe minimum ofpullotf travel which would not mark or otherwise damage the thread cut upon the work, and one that would close easily. Our head-fulfills all of these requirements and the mechanism for closing it will now be set forth.

Head operatingor closing mechanism Mounted for axial sliding movement on cylindrical portion 16 of support Sis an annular operating member or. ring I06 and it is secured ring has been pushed locking position the vention when it assumes this form. For instance against rotation thereon by means of a key I01. Ring I06 is provided with a conical rear face I08 and with a cylindrical outer surface I09 which telescopingly cooperates with flange 52 of the adjusting ring, so as to exclude extraneous matter from the mechanism.

The forward face of ring I06 is adapted to 'abut the rear face of locking ring L, but the two parts are normally urged apart by means of a plurality of compression springs II2, seating in recesses H3 in ring I06 (Figure 5). Springs II2 urge plungers II4 against the bottom of recesses H3 and react directly against the closing ring. The operating ring is accordingly maintained in the retracted position against a rear flange II5 provided on support S when the head is in locked condition and no forces are applied to the ring.

The operating ring I06 may be actuated in any suitable manner, but we preferably employ a rockable yoke having a pair of arms Ill! and which is mounted for rocking or sliding movement in any suitable manner (not shown). Upon each arm I" is mounted a pin II8 which rotatably supports a conical roller II9.

Head closing' operation With the head in the unlocked condition illustrated in Figure 7, arms II! are moved in any suitable manner by any suitable means forwardly so as to engage rollers HQ with the conical face I08 of ring I06. When this has been effected. rollers II9 start to revolve and upon further movement of the parts operating ring I06 is moved forwardly and pushes locking ring L forwardly, which produces synchronous forward movement of adjusting ring 45 and closing ring C, which causes faces 33 of prongs 28 to push the chaser holders inwardly. when operating ring I06 has been moved forward a predetermined distance, during the operation just described, the bottoms of recesses I23 engage the outer ends of levers I22 and move them forward, which causes the bifurcations I24 of the levers to move rear wardlyand engage the heads 91 of screws 98.

' Further forward movement of the locking operating ring causes levers I22 to pull bolt members 00 rearwardly, so that by the time the locking forward to its proper axial H head has also been pulled back to a position where the latches may snap into recesses 82 and cooperate with abutment faces '83 of prongs 00 of the head.

Although we have shown and described a die head for cutting external threads it is to be understood that the invention may be applied to heads for cutting internal threads,- and the appended claims are intended to. embrace our inthe chasers and chaser holders may be replaced by circular chasers and the prongs of the closing ring reversed so as to urge the chasers outwardly when the ring is moved forwardly.-

As previously mentioned, the chaser holders may be replaced by left-handed chaser holders and the chasers sharpened at their other ends when it is desired to employ the head for cutting left-hand threads.

We have accordingly provided a die head which will automatically open with a minimum of pulloff action when the thread is completed, which requires a low pull-ofl' pressure to open it thereby avoiding marking the flanks of the thread, and which also closes easily. Also, by reason of the novel head construction, the operating ring is always maintained in the same position.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a die head assembly, a head mounted for axial movement upon a support, said head carrying cutters mounted for movement thereon and having a control mechanism, including an axially movable member for moving them inwardly when said member is moved forwardly with respect to said head, resilient means tending to move said member rearwardly so as to allow said cutters to move outwardly, releasable means for locking said member forwardly against the action of said resilient means, means for automatically unlocking said releasable means when said head moves forwardly with respect to said support for permitting said resilient means to move said member rearwardly, and means for moving said member forwardly, for closing the die against the action of said resilient means, and for positively moving said head rearwardly with respect to said support.

2. The die head assembly described in claim 1, wherein said head is urged rearwardly with respect to said support by a second resilient means.

3. The die head assembly described in claim 1, wherein said last-named means is operable to synchronously move said member forwardly and said head rearwardly.

4. The die head assembly described in claim 1,

wherein said last-named means comprises at least one lever element fulcrumed upon said support and acting at one end against said head and having operative connection at the other end wiisth said member and a force applying mechan m.

5. The die head assembly described in claim 1, wherein said member for controlling said cutters comprises a ring surrounding a portion of said head and slidable thereon and said releasable means comprises a second ring abutting the rear face of said first ring and having a plurality of inwardly slidable latches cooperating with abutment faces provided on said head.

6. In a die head assembly, a head having an enlarged flange portion and a rearwardly extending shank portion, a plurality of chaserssupported on the flange portion of said head and mounted for movement toward and away from the axis oi said head, a ring member slidably mounted on the shank of said head and having operative connections with said chasers extending through the flange portion of said head, said ring member being operable to move said chasers inwardly when it is moved forwardly and operable to move said chasers outwardly when it is moved rearwardly, an annular element disposed rearwardly of said ring member, means for rigidly connecting said annular element to said ring member for compelling them to undergo synchronous axial movement, saidmeans permitting said ring member and said annular element to be axially adiusted with respect to each other, and resilient means acting upon said annular element and tending to urge it rearwardly, said resilient means being so related to said head that adjustment of said ring and element with respect to each other does not vary the stress therein.

7. The die head assembly described in claim 6, wherein said, annular element is. threaded directly to said ring member.

8. The die head assembly described in claim 6, wherein said annular element is telescoped over and is threadedly connected to said ring member and is in turn telescoped within, but slidably associated with; an axially directedflange provided on the flange portion of said head.

9. The die head assembly described in claim 6. wherein said resilient means comprises at least one compression spring acting against said annular element and reacting against the flange portion of said head, said spring projecting free through an aperture in said ring member.

10. The die head assembly described in claim 6. wherein said annular element and said ring member are threadedly connected and said ring member is non-rotatively secured to said head, and said resilient means comprises at least one compression spring acting against said annular element and reacting against the flange portion of said head, and having means associated therewith for preventing displacement thereof in response to adjustment of said annular element with respect to said ring member.

11. The die head assembly described in claim 6. wherein said annular element is telescoped with in an axially directed flange provided on the flange portion of said head and in turn is pro-. vided with an axially directed flange which is telescoped over a locking mechanism for selectively holding said ring member in forward position against the action of said resilient means.

12. In a die head assembly, a head having a closing ring axially slidable with respect thereto, a locking ring disposed rearwardly of said closing ring and mounted for free axial movement with respect to said head and said closing ring, said locking ring having latch means for looking it and said closing ring against rearward movement, means for rendering said latch means inoperative, an operating ring disposed rearwardly of said locking ring and mounted for axial movement with respect to said head and operable to engage and force said locking ring forwardly,

means for limiting rearward movement of said operating ring, and resilient means urging said locking and operating rings away from each other, thereby maintaining said locking ring :stantly engaged with said closing ring.

13. In a die head, a head having an enlarged portion, a plurality of chasers mounted for substantially radial sliding movement on the enlarged portion of said head, a control member mounted for axial movement on said head, said member having a plurality of prongs extending through the enlarged portion of said head and cooperating with said chasers, each of said chasers having a pair of cam faces which slidably cooperate with a pair of cam faces of each of said prongs, the cam faces of said prone: being for axial sliding movement on a support, a plu-' a ward movement on said head, a closing ring slidable axially with respect to said head and having operative connections with said chasers for causing said chasers to move inwardly into threading position when said ring is moved forwardly, and for causing said chasers to move outwardly to non-threading position when said closing ring is moved rearwardly, resilient means acting upon said ring and reacting against said head for urging said ring rearwardly, a plurality of inwardly and outwardly movable latch elements cooperating with abutments provided on said head, said latch elements being operable to hold said ring in forward position when they are disposed inwardly in engagement with said abutments, and means carried by said support and automatically operable to simultaneously move said latch elements outwardly from engagement with said abutments when said head is moved a predetermined distance with respect to said support, to thereby allow said resilient means to move said ring rearwardly and move said chasers outwardly, said latch elements being mounted for sliding movement in an annular member slidably mounted for axial movement on said head rearwardly of said closing ring and cooperating in direct contact with the latter, but being free to be moved away therefrom under certain conditions of. operation. I

16. The die head assembly described in claim 15, wherein the annular member, which is axially slidable on said head, is also non-rotatably associated therewith, and means for urging said annular member toward said closing ring.

1'7. In .a die head assembly, a head mounted for axial sliding movement on a support, movable chasers carried by said head, means for controlling movement of said chasers comprising a chaser controlling member mounted for movement axially of said head, at least one outwardly and inwardly movable latch element carried by said member and cooperating with an abutment provided on said head, said latch ele ment being operable to lock said member against axial movement when it is in its inner position in engagement with said abutment. said support having an actuating face inclined to the axis of said head for engaging the inner end of said latch element for automatically moving the same outwardly away from said abutment when said head is moved a predetermined axial distance with respect to said support, the abutment for said latch element being provided in an axially directed projection provided on said head, said.

cutter members mounted thereon, said head being provided at its periphery with an axially directed flange, a closing ring for controlling said cutter members mounted for axial sliding movement with respect to said, head and having a cylindrical portion nesting closely within, and telescopingly associated with the flange of said head, said closing ring having an axially directed flange, at its rear end, and a locking ring disposed rearwardlyof said closing ring and mounted for axial sliding movement with respect to said head, said locking ring cooperating in abutting relationship with said closing ring and hav- 4 ing at least one latch cooperating with said head for 'releasably looking it against axial movement, said locking ring nesting within the flange of said closing ring. I

19. In a die head assembly, a head carrying cutters and having a closing ring for controlling the action thereof, said head and closing ring being mounted for axial movement on a support, said closing ring having an axially directed flange, a locking ring nesting within said flange and operable to releasably lock said closing ring in a predetermined axial position with respect to said head, an operating ring mounted for axial sliding movement on said support and having a portion nesting closely within said flange for sealing the assembly against the entry of extraneous matter, said operating ring cooperating in abutting relationship with the rear face of said locking ring and adapted to effect axial movement thereof under certain conditions of operation.

20. In a die head assembly, a support, an operating ring; a die head; a closing ring and a locking ring mounted for axial movement with respect to said support, said operating ring being disposed between said locking ring and the rear end of said support, a plurality of substantially radially disposed levers fulcrumed upon said support, .a plurality of forwardly facing abutments provided on said' head for cooperation with the inner ends of said levers, said operating ring having a forwardly facing abutment cooperating with the rear face of said locking ring, said operating ring also having a plurality of forwardly facing abutments operating ring causes the same to contact said levers and effect rearward movement of said head.

wherein said abutment faces of said head comprises the heads of a plurality of bolt-like members secured to said head, and the inner ends of said levers are bifurcated so as to embrace the shank portions of said members. 23. The die-head assembly set forth in claim 20, together with a plurality of compression springs disposed between said locking ring and said operating ring for constantly urging the two apart.

24. In a die head assembly, a closing ring mounted for axial movement with respect-to a die head for controlling the cutters thereof and having an axially directed flange, a locking ring nesting within the flange of said closing ring and having a plurality of inwardly and outwardly slid- 22. The die head assembly set forth in claim 20,

being adapted for axial movement with respect to said closing ring, said latches cooperating with a plurality of latch faces provided on said head, and a plurality of springs for urging said latches inwardly, said springs reacting at their outer ends against the flange of said closing ring.

25. Inc. die head assembly having a head element and an axially movable closing ring mounted on said head element, a locking ring assembly associated with said closing ring and said head element comprising a ring member having a plurality of substantially radially extending opensided recesses provided in one side face thereof, a cover ring secured to said ring member and closing the open sides of said recesses so as to form a plurality of passages, a plurality of latches mounted for sliding movement in said passages, said latches being substantially rectangular in form and cooperating in surface engagement with the walls of said passages.

26. In a die head assembly, a head having a plurality of inwardly and outwardly movable cutters provided thereon, a closing ring mounted for axial sliding movement with respect to said head for controlling said cutters, said closing ring having a plurality of axially directed passages and being provided on its periphery with screw threads, a second ring encircling said closing ring and threadedly connected thereto, said second ring having an inwardly extending flange rearwardly of said closing ring, and a plurality of compression springs disposed in the axially directed' passages of said control ring and acting against said head and reacting against the flange of said second ring, for urging said closing ring rearwardly.

27. In a die head assembly, a support having a generally cylindrical shank and a smaller, generable latches provided therein, said locking ring ally cylindrical sleeve portion, a head mounted for axial movement on the sleeve portion of said support, said head having a cylindrical portion of the same diameter as the shank of said support, said shank of said support having a plurality of axially directed recesses in which are slidably guided for axial movement a plurality of axially directed fingers provided on the cylindrical portion of said head, for allowing said head to move axially on said support and preventing it from rotating with respect thereto, the said fingers of said head having substantially radially disposed faces cooperating with the walls of said recesses,

'and substantially cylindrical outer surfaces, a

closing ring, and a latch mechanism associated with said closing ring and slidably mounted on the cylindrical surfaces of said fingers, and the shank of said support adjacent said recesses, said latch mechanism having latches cooperating with a plurality of abutment faces provided on said shank and in the cylindrical surfaces of the fin gers of said head.

28. The die head assembly set forth in claim 27, wherein said latch mechanism comprises a ringlike member having a plurality of inwardly and outwardly slidable latches thereon, and which is slidably mounted for axial movement on the shank of said support adjacent said recesses and on the fingers of said head, and wherein the cylindrical surfaces of the shank portion of said support adjacent said recesses are provided with inclined cam faces for automatically moving said latches outwardly away from said abutment faces on said head into unlocked position when said head and support move axially with respect to each other a predetermineddistance.

SAMUEL W. MATHIAS. MILBU'RN A. HOLLENGREEN 

